• Journal of the Korean Data and Information Science Society
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• v.17 no.4
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• pp.1261-1270
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• 2006

This paper proposes a mobile computing prefetching method providing the effective information about location change of mobile user or mobile computing in mobile information services. For mobile computing environments, there exist restrictions as like low bandwidth, latency and traffic. To solve those problems, a variety of techniques have been developed including caching and prefetching. In this paper we present a Statistical Poisson Prefetching Scheme using the reference count to provide a mobile user information that will be likely referenced in the near future. Comparing to existing methods in numerical results, the proposed method improves the prefetching performance to give the maximum effectiveness and reduces the failure rate of information searching.

• International Journal of Internet, Broadcasting and Communication
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• v.10 no.3
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• pp.42-50
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• 2018

The majority of existing falling recognition techniques provide service by recognizing only that the falling occurred. However, it is important to recognize not only the occurrence of falling but also the situation before and after the falling, as well as the location of the falling. In this paper, we design and propose the falling notification service system to recognize and provide service. This system uses the acceleration sensor of the smartphone to recognize the occurrence of a falling and the situation before and after the falling. In order to check the location of falling, GPS sensor data is used in the Google Map API to map to the map. Also, a crosswalk map converted into grid-based coordinates based on the longitude and latitude of the crosswalk is stored, and the locations before and after falling are mapped. In order to reduce the connection speed and server overload for real-time data processing, fog computing and cloud computing are designed to be distributed processing.

• Journal of the Korea Society for Simulation
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• v.15 no.4
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• pp.11-19
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• 2006

With the emergence of pervasive computing, personalization becomes an important issue to provide with users customized services, anywhere and anytime in their specific environment. Many researches have shown the possibilities of personalization by acquiring and processing sensor information around users. However, personalization remains still at its infancy, since most researches have failed to consider various contexts comprehensively besides sensor data, and just developed tailored services for a specific application domain. In this work, we propose a simulation-based CAS (context Aware Web Services) development methodology. Our methodology considers various contexts on users (eg. current location), web services (eg. response time), devices (eg. availability) and environment (eg. sensor data) all together by simulating them on the fly for personalized and adaptable services.

• Review of KIISC
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• v.15 no.5
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• pp.100-112
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• 2005

유비쿼터스의 주요한 특성은 상황 인식(Context-Aware)이며 이것은 사용자의 시공간에 따라 변하는 데이터를 사용자가 직접 입력하지 않고 상황에 맞게 자동적으로 처리해 주는 것을 뜻한다. 그러나 이러한 유비쿼터스의 특성은 데이터의 보안이 취약할 경우 기존 컴퓨팅 환경보다 더 큰 문제를 가져올 수 있다. 한편, 미 벨 연구소에 의해 개발된 PCP(Privacy Conscious Personalization)는 모바일 및 유비쿼터스 환경에서 사용자의 프라이버시 문제에 Context-Aware의 특성을 반영해 준다. PCP는 위치 정보에 대한 요구를 받으면 Houdini로 명명된 Rule Engine을 작동시키며 현재의 상황 및 사용자의 설정을 고려하여 정보를 공개할지 여부를 결정한다. 또한, 네덜란드의 University of Twente는 P3P를 확장하는 P3P Extension과 상황-의존 Preference를 표현하는 XML 기반 언어를 개발하고 이를 바탕으로 WASP 플랫폼을 위한 아키텍쳐를 개발하였다. WASP Framework는 웹서비스 기반의 프라이버시 보호 아키텍쳐이며 사용자의 위치, 시간, 상태, 신원 등 다양한 Context 정보를 제공할 수 있다. 본고에서는 Location Context의 관점에서 Context Aware Computing 환경의 하나로 LBS 위치정보의 프라이버시 구조에 대한 두가지 사례 연구를 수행한다.

• Proceedings of the Korean Information Science Society Conference
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• 2010.11a
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• pp.56-57
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• 2010

• Proceedings of the KAIS Fall Conference
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• 2003.11a
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• pp.231-235
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• 2003

Network infrastructure has spread to an unprecedented extent and is used in various computing devices, such as smart appliances, smart phones, and embedded devices with sensors, which have all been appearing in the computing environment. To accommodate this trend, for a more intelligent service environment, the service platform needs to have abilities that facilitate the operation between services, dynamically share distributed computing resources, and manage appropriate contextual information. We have simulated a service platform to provide intelligent services using contextual information after having implemented the context management service. The context management service gathers raw contextual information from sensors and stores these in the context database. For a consistent basis of contextual information, time and location are used as the key values of the contextual information. The context management service also performs normalization to provide computable contextual information to context-aware applications. In this paper, a service platform based on Jini technology is proposed for constructing an interoperable, dynamic, and . intelligent service environment using contextual information.

• Journal of Internet Computing and Services
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• v.5 no.2
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• pp.75-84
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• 2004

Geocasting, a variant of the conventional multicasting problem, is one of communication type in which the data packets are delivered to a group of all nodes within a specified geographical region (i.e., the geocasting region) and is called location-based multicasting(LBM)(l). An Ad-hoc network is a dynamically reconfigurable and temporary wireless network where all mobile devices using batteries as energy resources cooperatively maintain network connectivity without central administration or the assistance of base stations. Consequently, the technique to efficiently consume the limited amounts of energy resources is an important problem so that the system lifetime is maximized. In this paper, we propose a LBPA(Location-Based Power Aware) geocasting algorithm that selects energy-aware neighbor to route a packet towards the target region In Ad-hoc network environments. The method Is such that the energy consumption is balanced among the nodes in proportion to their energy reserves. Through the simulations, the proposed LBPA algorithm shows better results, that is, as good as 40% on the average over the conventional LBM algorithm in terms of the network lifetime.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.5
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• pp.486-494
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• 2014

Intelligent homes consist of ubiquitous sensors, home networks, and a context-aware computing system. These homes are expected to offer many services such as intelligent air-conditioning, lighting control, health monitoring, and home security. In order to realize these services, many researchers have worked on various research topics including smart sensors with low power consumption, home network protocols, resident and location detection, context-awareness, and scenario and service control. This paper presents the real-time metabolic rate estimation method that is based on measured heart rate for human adaptive appliance (air-conditioner, lighting etc.). This estimation results can provide valuable information to control smart appliances so that they can adjust themselves according to the status of residents. The heart rate based method has been experimentally compared with the location-based method on a test bed.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.177-178
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• 2006

The real-time tracking system is an essential factor for the development of low cost sensor networks for use in pervasive computing and ubiquitous networking. In this paper, we address the interference problems of the sensor network platform with ultrasonic for location tracking system. Ubiquitous indoor environments often contain substantial amounts of metal and other such reflective materials that affect the propagation of radio frequency signals in non-trivial ways, causing severe multi-path effects, dead-spots, noise, and interference. Especially we present a novel reducing interference location system that is particularly well suited to support context-aware computing. The system called Pharos, aims to combine the advantages of real-time tracking systems that implement distributed environment with regardless of infrastructure or infrastructure-less wireless sensor networks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.7
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• pp.1740-1746
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• 2013

Augmentative and alternative communication(AAC) is a communication tool for those with impairments or restrictions on the production or comprehension of spoken language. Traditional AAC has used a portable board with pictures and texts with which disabled person could be supported by it. Currently, smart phone based AAC researches and developments are actively studying. With emerging concepts of context-aware computing, the mobile devices can provide mobile users with timely information and location based services. We proposed a adjustable AAC system for disabled people of which has variable layouts and selectable items. We also implemented context-ware application for AAC systems including time, location and click count informations on smart phone. The system can adaptively change its layout and select AAC items depending on various situation of disabled persons.